During performances of music, there is a group of musicians each playing different instruments together to provide a song. Often, the songs that are performed are done so many times throughout the life of the group of musicians playing together. It is common or desirable to alter or change the structure of the song, sometimes morphing into a different song altogether during the performance. Many jazz compositions leave room during the performance to allow an individual performer to perform solo.
Occasionally, multiple performers can go “off-script” as well. Although these types of performances lack a specific structure and enable individualism to shine through, some sort of conformity or indication is preferable during the performance. If one (1) individual is playing off tempo or in another key to provide a dissonant and unattractive sound, it could distract from the performance. Thus, there is a need to provide a way to indicate tempo and upcoming key changes, amongst other musical styles, during a musical performance.